Torque reaction devices for dissipating energy with a pump-like apparatus are well known to those skilled in the art as evidenced by the above mentioned prior art references. Energy dissipators which avoid frictional metal to metal contact, such as mechanical brakes for example, utilize a circulating noncompressible fluid which is caused to flow between pockets of a stator and rotor thereby providing a torque reaction device which serves as a brake.
In the oil field, where oil wells are drilled far down into the earth, the drawworks of rotary drilling rigs require that energy be rapidly dissipated in order to immediately arrest the fall of pipe going into the wellbore with a rapid, uniform deceleration. There are many other examples where dynamic braking is desired, as for example, a dynamometer associated with a large diesel truck.
Hydrodynamic braking involves the dissipation of power into a noncompressible fluid, as may be achieved by a pump device, and provides a more uniform deceleration of rotating parts. For this reason, it is desirable to employ hydrodynamic braking for decelerating the movement of pipe associated with a drilling rig.